The present invention relates to a power unit and an image forming apparatus to which the power unit is mounted. The power unit is usable with an image forming apparatus using an electrophotographic type, electrostatic recording type or the like process. The power unit is optionally installed in the image forming apparatus such as a copying machine, printer or the like when the user desires.
Referring to FIGS. 9 and 10, a conventional example will be described.
In this conventional example, the main assembly 110A comprises an original reading station (reader apparatus) 105A and an image formation station (printer) 106A.
The copying image formation will be briefly described. Image information is obtained by scanning an original using the reader apparatus 105A. A photosensitive member is uniformly charged by charging means, and the surface of the photosensitive member is exposed to the image information by exposure means to form an electrostatic latent image to develop the electrostatic latent image by a developing device. A recording paper is fed from a sheet feeding cassette 1 disposed at a lower portion of the main assembly, and the developed image provided by the developing device is transferred onto the recording paper by transferring means. The recording paper now having the image transferred thereonto is fed to a fixing device, which fixed the image on the recording paper and discharges the recording paper to the outside.
The description will be made as to conventional structure around a power unit which is an option apparatus (option voltage source) detachable to the main assembly of the image forming apparatus.
FIG. 9 is a rear view of the option apparatus and the main assembly of the image forming apparatus. Designated by 110A is the main assembly of the image forming apparatus; 111A is an original feeder apparatus which is one kind of an option apparatus for feeding an original to be copied to the image reading station; 112A is a cassette pedestal apparatus which is one kind of an option apparatus for feeding sheets to the image forming apparatus, the cassette pedestal apparatus being provided with a sheet feeding device and a sheet feeding cassette described in conjunction with FIG. 6; 113A is paper-deck apparatus which is one kind of an option apparatus for feeding sheets to the image forming apparatus, the paper-deck apparatus 113A having a function of feeding the sheets; 114A is a finishing apparatus which is an option apparatus for aligning, stapling and/or sorting the sheets discharged from the main assembly of the image forming apparatus; 115A is a first voltage source cable for supplying electric power to the feeder apparatus 111A from the main assembly 110A of the apparatus; 116A is a first connector for connecting the first voltage source cable 115A to the main assembly of the apparatus; 117A is a second voltage source cable for supplying electric power from the main assembly 110A of the apparatus to the cassette pedestal apparatus 112A; 118A is a second connector for connecting the second voltage source cable 117A to the main assembly of the apparatus; 119A is a third voltage source cable for supplying electric power to the paper deck apparatus 113A from the main assembly 110A of the apparatus main assembly of the apparatus; 120A is a third connector for connecting the third voltage source cable 119A to the main assembly of the apparatus; 121A is a fourth cable for supplying electric power to the finishing apparatus 114A from the main assembly 110A of the apparatus; 122A is a fourth connector for connecting the fourth voltage source cable 121A to the main assembly of the apparatus; and 123A in an outer casing of the main assembly of the apparatus. The first, second, third and fourth connectors are disposed in the main assembly 100A of the copying image forming apparatus.
FIG. 10 shows an inside of the main assembly of the apparatus, omitting the outer casing 123A. In FIG. 10, designated by 124A is a main voltage source for supply 24V in the main assembly 110A of the apparatus; 125A is a low and high voltage source for supplying a low voltage not more than 23V such as 3, 5, 13V or the like and a high voltage such as not less than 100V in the main assembly of the apparatus; 126A is a DC voltage source for supplying a starting and stopping signal to each of the driving source in the main assembly of the apparatus in FIG. 10; and 107A is a reader controller for controlling an original reading operation of the main assembly of the apparatus.
Here, the cassette pedestal apparatus 112A is supplied with a control signal from the DC voltage source 126A of the main assembly of the apparatus and with electric power from the low and high voltage source (124A, 125A) through the second connector 118A and the second voltage source cable 117A. Designated by 127A is an option voltage source, detachable to the main assembly 110A of the apparatus, for providing a voltage source (24V, 5V or the like) for driving each of the option apparatus (11A, 113A, 114A). Driving. The option voltage source 127A is disposed adjacent the original feeder apparatus 111A which is most often used among the option apparatuses (111A, 113A, 114A) except for the cassette pedestal apparatus 112A. The original feeder apparatus 111A is supplied with a control signal from the reader controller 107A and with the driving electric power from the option voltage source through the first connector 116A and the first cable 115A. The paper deck apparatus 113A and the finishing apparatus 114A are supplied with a control signal from the DC voltage source 126A and with the driving electric power from the option voltage source through the third and fourth connectors (120A, 122A) and the third and fourth cables (119A, 121A).
Depending on the structure of the option voltage source, (1) the cassette pedestal apparatus 112A may be supplied with the electric power from the option voltage source 127A, (2) some of the option apparatuses (111A, 112A, 113A, 114A) may be supplied with electric power from the main voltage source 124A of the main assembly, and the other may be supplied with the option voltage source.
As shown in FIGS. 9, 10, in the conventional structure, the option voltage source 127A is detachable relative to the main assembly 110A of the apparatus, and it is loaded in the main assembly of the apparatus only when an option apparatus to be driven by the option voltage source 127A. By doing so, the cost of the main assembly 110A is lowered, and the user not requiring the option apparatus is free from additional cost. In addition, by reducing the number of cables directly connected to the electrical outlet, the number of change devices required for permitting use in areas providing different voltages, can be reduced.
However, in a conventional system, the electric power is supplied from one option voltage source to all of the option apparatuses. Therefore, the original feeder apparatus and the cassette pedestal apparatus which are relatively frequently used and the cassette deck and the finishing apparatus which are relatively less frequently used, are supplied with the electric power from the same option voltage source. This is so in order to reduce the cost of the main assembly of the apparatus. Despite the fact that it is intended to reduce the cost imparted to the user not requiring the option apparatus, the option voltage source apparatus is such as to cover all of the option apparatuses, and therefore, is expensive. For example, the same option voltage source apparatus has to be used even when the original feeder apparatus and/or the cassette pedestal is used, but the cassette deck or finishing apparatus is not used. The connector (116A, 118A, 120A, 122A) to which the conventional option apparatus (111A, 112A, 113A, 114A) is connected, is disposed at a position close to the option apparatus away from the option voltage source. Therefore, when the option voltage source is mounted to the main assembly of the apparatus, a connector to which the option apparatus is connected has to be installed, with the result of time consuming operations. In another case, the connector is provided in the main assembly of the apparatus irrespective of whether the option apparatus is mounted or not. This leads to cost increase of the main assembly of the apparatus, and therefore, the advantage of the option voltage source apparatus intended to reduce the cost is not provided enough.
Accordingly, it is a principal object of the present invention to provide a power unit and an image forming apparatus to which the power unit is mounted, wherein an operativity upon mounting is high.
It is another object of the present invention to provide an image forming apparatus with which the cost is reduced with the high operativity upon the mounting of the power unit.
It is a further object of the present invention to provide an electric power unit for an option apparatus selectively mountable to an image forming apparatus, wherein the power unit is mounted to the image forming apparatus with mounting of the option apparatus, includes an electric power generating portion for generating electric power; and a connector for connection with the option apparatus to supply electric power from the electric power generating portion to the option apparatus.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.